I have successfully sealed a cracked castiron head that was leaking water into the oil with K Seal. The lift truck was used for another 10 years after the K Seal with a cracked head. The oil and water stayed separate after that till I got rid of the lift truck. Sure helped with the resale value too.
Water Glass (Sodium Silicate) is another good sealer/repair. I suspect it may be the active ingredient in K Seal if it sealed up a cracked head.
It needs to be used with caution tho.
https://en.wikipedia.org/wiki/Sodium_silicateKevin
